Rotary combustion engine

ABSTRACT

A rotary combustion engine having an internal gas flow control providing gas flow from a trailing to a leading portion of each working chamber during the latter portion of a compression phase when communication between such portions becomes substantially limited between the stator housing&#39;&#39;s peripheral wall and the rotor face and the gas flow control in addition preventing back flow from a leading chamber to a trailing chamber.

United States Patent Fleming ROTARY COMBUSTION ENGINE PrimaryExaminer-Carlton R. Croyle Assistant Examiner-Michael Koczo, Jr.

[75] Inventor: James Fleming warren Mich' Attorney JfL. Carpenter and R.L. Phillips et a]. [73] Assignee: General Motors Corporation,

Detroit, Mich. [57] ABSTRACT [22] Filed: May 1972 A rotary combustionengine having an internal gas flow [21] Appl. No.: 250,317 controlproviding gas flow from a trailing to a leading portion of each workingchamber during the latter portion of a compression phase whencommunication be- 123/8.4: b2l:35/)(l)i tween Such portions becomessubstantially limited 58] i 'i' 8 31 8 27 tween the stator housingsperipheral wall and the rotor are face and the gas flow control inaddition preventing back flow from a leading chamber to a trailing cham-[56] References Cited UNITED STATES PATENTS 3 Claims, 3 Drawing Figures3,463,126 8/1969 Pax 123/827 IGNITION \J, 70 g 46 CONTROL l SYSTEM g 46O Q I O 5 v C \F 5;: y g i m w h I I O I j -7- Q E 26 9 I avg 28 0 70 2A- 2 a O v w I O w as 46 BQg W w PATENTEU M1828 I915 ROTARY COMBUSTIONENGINE This invention relates to rotarycombustion engines and moreparticularly to rotary combustion engines having internal gas flowcontrol.

In rotary combustion engines of the Wankel type it is conventionalpractice to provide a recess in each rotor face which forms asubstantial part of the com bustion space in each working chamber andalso serves as a flow path for gas flow from a trailing portion to aleading portion of each chamber when the communication between suchchamber portions would be substantially limited by the clearance betweenthe rotor face and the stators peripheral wall during the final portionof compression. The gas flow requirements for removal of gas from thetrailing portion to the leading portion restrict the shape and locationof the combustion space in each rotor face with the result that thechamber may not be best shaped and located for the combustion process.

The rotary combustion engine according to the present invention has aninternal gas flow control that permits a choice of shape and location ofthe combustion space in each rotor face apart from the gas flowrequirements between the trailing and leading portion of each workingchamber but does not provide a leakage path between any two workingchambers. In one embodiment of the present invention this is provided bya gas flow passage in the engine housing having leading and trailingopenings through the housings internal peripheral wall of the rotorcavity for connecting the trailing portion to the leading portion ofeach working chamber during the final portion of compression. Inaddition there is provided a one-way valve in this gas flow passage thatprevents connection between a leading chamber and a trailing chamberwhenever the leading chamber has a higher pressure.

An object of the present invention is to provide a new and improvedrotary combustion engine.

Another object is to provide in a rotary combustion engine an internalgas flow control that permits a choice of shape and location of acombustion space in each rotor face independent of the requirements forgas flow between a trailing portion and a leading portion of eachworking ,chamber during compression.

Another object is to provide in a rotary combustion engine a gas flowpassage in the engine's housing that provides for gas flow from atrailing portion to a leading portion of each working chamber duringcompression and prevents connection between a leading chamber and atrailing chamber whenever the leading chamber has a higher pressure.

Another object is to provide a rotary combustion engine having aninternal gas flow control that directs gas from a trailing portion ofeach working chamber through the engine's housing to a leading portionof this same chamber during compression and furthennore has a one-wayvalve that prevents flow from a leading chamber to a trailing chamberwhenever the leading chamber has a higher pressure.

These and other objectof the present invention will be more apparentfrom the following description and drawing in which:

FIG. 1 is a fragmentary transverse sectional view of a rotary combustionengine having an internal gas flow control according to the presentinvention.

FIG. 2 is an enlarged view of the internal gas flow control in FIG. 1.

FIG. 3 is a view taken on the line 3-3 in FIG. 2.

Referring to FIG. 1, the present invention is particularly suited foruse in a Wankel type rotary combustion engine comprising a stationaryhousing 10 having an inwardly facing peripheral wall 12 and a pair ofopposed end walls 14, of which only one is shown, cooperatively defininga cavity 16. The peripheral wall 12 is in the shape of a two-lobedepitrochoid or a curve parallel thereto whose center is indicated at 18and comprises a pair of lobes 20 and 22 which are bisected by the curvesmajor axis 24 and a pair of cusps 26 and 28 which are bisected by thecurves minor axis 30 with the minor axis and the major axis intersectingat right angles at the center 18. A crankshaft 32 is rotatably mountedin the engine housing 10 so that its axis is conincident with the center18 and has an eccentric 34 located in the rotor cavity 16 with itscenter line 36 offset from and parallel to the crankshaft axis.

A three-lobed rotor 38 having the general shape of a triangle with threearcuate faces 40 facing the peripheral wall 12 is mounted on thecrankshaft eccentric 34 for rotation about the eccentric center line 36.The rotor faces 40 cooperate with the peripheral wall 12 and with theend walls 14 to define three variable volume working chambers 42 thatare spaced about the rotor and move with the rotor within the enginehousing. Chamber scaling is provided by an apex seal '44 mounted at eachapex or corner of the rotor 38, a side seal 46 mounted on each rotorside extending adjacent each rotor face between each set of adjacentapex seals 44 and an intermediate corner seal 48 mounted 'on each rotorside at each rotor apex providing a sealing link between the adjacentends of the two side seals and the apex seal at this rotor apex. Theapex seals 44 are biased by biasing means, not shown, to continuouslyengage the peripheral wall 12 and both the side seals 46 and cornerseals 48 are biased by biasing means, not shown, to engage the end wallswith the complete sealing arrangement acting to seal the workingchambers from each other. With the two-lobed peripheral wall 12 and thethree apex rotor 38, there are provided the four phases of intake,compression, expansion and exhaust in each chamber in fixed relation tothe housing when the rotor is forced to rotate at one-third the speed ofthe output shaft. This is accomplished by a timing gear train betweenthe rotor 38 and the housing 10 which comprises an internally toothedring gear 50 which is concentrically mounted on one side of the rotor38. Ring gear 50 meshes with an externally toothed ring gear 52 which isconcentric with and freely received about the crankshaft 32 and is fixedby securing means, not shown, to the housing 10. The ring gear 50 has Iand A times the number of teeth as the gear 52 to provide the requiredratio of 3:1 between the crankshaft and rotor.

The engine further has an induction system comprising an intake manifold54 that is secured to the engine housing 10 and receives an air-fuelmixture from a co'nventional carburetion system, not shown, and deliversthis air-fuel mixture to an intake port 56 which opens to the rotorcavity 16 through one of the end walls 14 at a location on one side ofcusp 26 to one side of and near the minor axis 30 and to one side of themajor axis 24. It will also be understood that there may be anotherintake port identical to and opposite the intake port 56 in the oppositeend wall. With this arrangement, airfuel mixture is periodicallyadmitted to each working chamber 42 by one side of the rotor uncoveringthe intake port to each working chamber while it is expanding during itsintake phase. Combustion is initiated by a pair of sprak plugs 58 and 60which are mounted in the engine housing so that their electrodes areopen to the rotor cavity on opposite sides of the other cusp 28. Withrotor rotation in the direction indicated by the arrow in FIG. 1, thespark plug 58 is commonly referred to as the trailing plug and the otherspark plug 60 is commonly referred to as the leading spark plug. Voltageis applied to the spark plugs 58 and 60 from a DC. supply 62 by anignition control system 64 which may be of any suitable type thatoperates to supply voltage simultaneously to both plugs and also to onlyone or the other of the plugs during certain operating conditions as iswell known in the art, the timing being such that sparking occurs eachtime the rotor 38 is in the vicinity of one of its three top-dead-centerpositions as shown in dashed line in FIG. 1 with the associated workingchamber having undergone its compression phase. After the workingchamber has undergone its expansion phase on the occurrence ofcombustion and with continued rotor rotation, the products of combustionare exhausted by an exhaust manifold 66 that is secured to the housing10 and has an exhaust port 68 open to the rotor cavity 16 through theperipheral wall 12 at a location on the side of cusp 26 opposite wherethe intake port 56 is located, i.e., the exhaust port 68 is located onthe same side of the major axis 24 as the intake port 56 but on theopposite side of and near the minor axis 30. In this exhaust portposition, the rotor apexes thus periodically open the chambers thattrail them to the exhaust passage during the exhaust phase while thechambers are undergoing contraction.

In engines of this type there is generally provided a cavity or recess70 in each rotor face 40 that forms part of the working chamber. Thecompression ratio may be varied by varying the size of the recess 70 andfurthermore, its location and shape may be varied to control thecombustion process as is well known in the art. However, apart fromaffecting the compression ratio and the combustion process, this recessis normally located centrally of the rotor face and elongated in adirection transverse to the rotor axis since it is required to maintainconnection between the leading and trailing portions or regions of theworking chamber when such communication becomes restricted by the cusp28 during the compression phase as the rotor face of the chamberapproaches top-dead-center position. As a result, the shape andlocationof the recesses 70 on the rotor faces 40 have been restricted by thenecessity of having to remove the gases from the so-called squish areabetween the trailing portion of the chamber and the peripheral wall asthe cusp 28 is approached and the clearance between the rotor face andthe peripheral wall closes.

The gas flow control according to the present invention incorporated inthe above disclosed engine comprises one-way gas passage means in therotor housing 10 that has openings to the rotor cavity for effecting gasflow from the trailing portion to the leading portion of each workingchamber in the vicinity of the chambers top-dead-center rotor positionand prevents back-flow from a leading chamber to a trailing chamber whenan apex seal traverses the area between these passage openings to therotor cavity. The gas passage means comprises a pair of gas passages 74that follow an arcuate path across the minor axis 30 past the cusp 28 asviewed in FIG. 2 and are axially spaced on opposite sides of the sparkplugs 58 and 60 as viewed in FIG. 3. Each of the gas passages 74 asshown in FIG. 2 has an inlet 76 that is open to the rotor cavity 16through the peripheral wall 12 on the trailing spark plug side of thecusp 28 and minor axis 30 and an outlet 78 that is open to the rotorcavity 16 through the peripheral wall 12 on the leading spark plug sideof the cusp 28 and the minor axis 30, both the inlet 76 and the outlet78 of the gas passage 74 being spaced along the peripheral wall 12 adistance substantially less than that spanned by a rotor face when inthe vicinity of top-dead-center. In addition, there is provided in eachgas flow passage 74 a check valve 80 that permits flow in the directionfrom the inlet 76 toward the outlet 78 and prevents flow in the oppositedirection. Each check valve 80 comprises, as shown in FIGS. 2 and 3, avalve seat member 82 tht is press fitted in the passage 74 and has acentral valve opening 84 which is closable by a ball valve 85 engageablewith the valve seat 82. When the pressure at inlet 76 is higher thanthat at outlet 78, the gas pressure dif ferential moves ball valve 85 toan open valve position against a limit stop provided by a single pin 86extending transverse through both of the gas passages axially of theengine housing. Alternatively, when the pressure at the outlet 78 ishigher than that at the inlet 76, the gas pressure differential movesball valve 85 against seat 82 to close valve opening 84 to preventreverse gas flow.

On operation of the rotary combustion engine with the gas flow controlaccording to the present invention during the compression phase when therotor 38 is approaching one of its top-dead-center positions with one ofthe working chambers then being divided by the cusp 28 and this chambersrotor face into a trailing portion and a leading portion, the leadingportion will be increasing in volume on continuing rotor motion whilethe trailing portion is reducing in volume. When the gas pressure in thetrailing portion exceeds the gas pressure in the leading portion thevalves 80 are opened by this gas pressure differential and gas in thecontracting trailing portion is then forced in the direction indicatedby the arrow through the gas flow passages 74 into the expanding leadingportion of this working chamber. This gas flow in the direction of rotorrotation through the gas flow passages 74 continues so long as the gaspressure differential between inlet and outlet forces such flow. Thenwhen the trailing apex seal of this working chamber has traversed theinlet 76 of the gas flow passages 74 as shown by the full line rotorposition in FIG. 1, backflow from the then leading chamber to the thentrailing chamber forced by the pressure in the leading chamber beinghigher than that in the trailing chamber is prevented since this pressure differential forces the valves 80 to close. Then on continued rotorrotation this trailing apex seal will eventually traverse the outlet 78of the gas flow passages 78 at which time both the inlet and outlet ofthe gas flow passages are open to the next working chamber to repeat thegas flow control cycle. It will also be appreciated that more or lessgas passages may be used to provide a flow area meeting the gas flowrequirement. Since the gas flow control of the present inventionprovides for removing gases from the squish area between the rotor facesand housing, there is no restriction in that regard as to the shape andlocation of the combustion spaces in the rotor faces best suited for thecombustion process.

The above described embodiment is illustrative of the invention whichmay be modified within the scope of the appended claims.

I claim:

1. A rotary combustion engine comprising a housing having opposing endwalls and a multilobed peripheral wall defining a cavity, a crankshaftrotatably supported in said housing having an eccentric located in saidcavity, a multiface rotor rotatably mounted on said eccentric andcooperating with said walls to provide a plurality of chambers that arespaced about and move with said rotor while varying in volume as saidrotor and said crankshaft rotate with each of said chambers during onerotor revolution sequentially undergoing expansion and compressionphases at least twice, an intake port open to said cavity at a locationto be periodically connected to each of said chambers during a firstexpansion phase, each said chamber being separated into a leadingportion and a trailing portion by a cusp portion of said peripheral wallafter a first compression phase following'said first expansion phase,ignition means for periodically effecting a spark in each of saidchambers after said first compression phase, an exhaust port open tosaid cavity at a location to be periodically connected to each of saidchambers during a second compression phase following a second expansionphase, and passage means including one-way'valve means having an inletand an outlet opening to said cavity for connecting the trailing portionto the leading portion of each said chamber during the final portion ofsaid first compression phase and preventing connection between a leadingchamber and a trailing chamber.

' 2. A rotary combustion engine comprising a housing having a pair ofopposed end walls and a peripheral wall defining a cavity, saidperipheral wall having basically the profile of an epitrochoid with twolobes and two cusps, a crankshaft rotatably supported in said housinghaving an eccentric located in said cavity, a rotor rotatably mounted onsaid eccentric having basically theprofile of a triangle having threeperipheral faces facing said peripheral wall, gear means between saidrotor and said housing for providing a fixed speed ratio between saidrotor and said crankshaft whereby said crankshaft is caused to rotatethree revolutions for every rotor revolution, said rotor faces and saidhousing walls cooperatively providing three working chambers that arespaced about and move with said rotor while varying between a minimumvolume at said cusps and a maximum volume intermediate said cusps assaid rotor and said crankshaft rotate and wherein each said chamber whenat minimum volume is divided by the then-associated cusp into a leadingportion and a trailing portion, an intake port open to said cavity at alocation to one side of one of said cusps so as to be periodicallyconnected to each of said working chambers, an exhaust port open to saidcavity at a location on the other side of said one cusp so as to beperiodically connected to each of said chambers, ignition means forperiodically effecting a spark in each of said chambers when adjacentthe other cusp, and passage means including one-way valve means in saidhousing for permitting gas-flow from said trailing portion to saidleading portion of each of said chambers past said other cusp andpreventing gas flow from a leading chamber to a trailing chamber.

3. A rotary combustion engine comprising a housing having opposed endwalls and a peripheral wall defining a cavity, said peripheral wallhaving basically the profile of an epitrochoid with two lobes and twocusps, a crankshaft rotatably supported in said housing having aneccentric located in said cavity, a rotor having basically the profileof a triangle with three apexes and three peripheral faces facing saidperipheral wall rotatably mounted on said eccentric, means for providinga fixed speed ratio between said rotor and said crankshaft so that saidcrankshaft is caused to rotate as said rotor planetates with a fixedcyclic relationship of three crankshaft revolutionsfor every rotorrevolution, said rotor faces and said housing wallscooperatively'providing three chambers that are spaced about and movewith said rotor while varying in volume as said rotor and saidcrankshaft rotate and-reaching a minimum volume when the associatedrotor face is exactly opposite one of the cusps which then divides thechamber into a trailing portion and a leading portion and reaching amaximum volume intermediate the cusps, an intake port open to saidcavity at a location on one side of one of said cusps so as tobeconnected to deliver a gas to said chambers, a spark plug mounted insaidhousing having an electrode open to said cavity at a' location adjacentthe other cusp so as to be periodically exposed to said chambers whenthey span saidother cusp, a passagein said housing having an inlet openat one end to said cavity at a location on one side of said other cuspand an outlet open at the other end to said cavity at a location on theother side of said other cusp to provide for connection between thetrailing and leading portions of said chambers when they span said 7other cusp, a one-way valve in said passage'for permitting gas flow fromthe trailing portion to the leading portion of said chambers when theyspan said other cusp and preventing gas flow from a leading chamber to atrailing chamber when a rotor apex is intermediate said inlet and saidoutlet, and an exhaust port open to said cavity at a location on theother side of said one cusp so as to be periodically connected toexhaust said chambers.

1. A rotary combustion engine comprising a housing having opposing endwalls and a multilobed peripheral wall defining a cavity, a crankshaftrotatably supported in said housing having an eccentric located in saidcavity, a multiface rotor rotatably mounted on said eccentric andcooperating with said walls to provide a plurality of chambers that arespaced about and move with said rotor while varying in volume as saidrotor and said crankshaft rotate with each of said chambers during onerotor revolution sequentially undergoing expansion and compressionphases at least twice, an intake port open to said cavity at a locationto be periodically connected to each of said chambers during a firstexpansion phase, each said chamber being separated into a leadingportion and a trailing portion by a cusp portion of said peripheral wallafter a first compression phase following said first expansion phase,ignition means for periodically effecting a spark in each of saidchambers after said first compression phase, an exhaust port open tosaid cavity at a location to be periodically connected to each of saidchambers during a second compression phase following a second expansionphase, and passage means including one-way valve means having an inletand an outlet opening to said cavity for connecting the trailing portionto the leading portion of each said chamber during the final portion ofsaid first compression phase and preventing connection between a leadingchamber and a trailing chamber.
 2. A rotary combustion engine comprisinga housing having a pair of opposed end walls and a peripheral walldefining a cavity, said peripheral wall having basically the profile ofan epitrochoid with two lobes and two cusps, a crankshaft rotatablysupported in said housing having an eccentric located in said cavity, arotor rotatably mounted on said eccentric having basically the profileof a triangle having three peripheral faces facing said peripheral wall,gear means between said rotor and said housing for providing a fixedspeed ratio between said rotor and said crankshaft whereby saidcrankshaft is caused to rotate three revolutions for every rotorrevolution, said rotor faces and said housing walls cooperativelyproviding three working chambers that are spaced about and move withsaid rotor while varying between a minimum volume at said cusps and amaximum volume intermediate said cusps as said rotor and said crankshaftrotate and wherein each said chamber when at minimum volume is dividedby the then-associated cusp into a leading portion and a trailingportion, an intake port open to said cavity at a location to one side ofone of said cusps so as to be periodically connected to each of saidworking chambers, an exhaust port open to said cavity at a location onthe other side of said one cusp so as to be periodically connected toeach of said chambers, ignition means for periodically effecting a sparkin each of said chambers when adjacent the other cusp, and passage meansincluding one-way valve means in said housing for permitting gas flowfrom said trailing portion to said leading portion of each of saidchambers past said other cusp and preventing gas flow from a leadingchamber to a trailing chamber.
 3. A rotary combustion engine comprisinga housing having opposed end walls and a peripheral wall defining acavity, said peripheral wall having basically the profile of anepitrochoid with two lobes and two cusps, a crankshaft rotatablysupported in said housing having an eccentric located in said cavity, arotor having basically the profile of a triangle with three apexes andthree peripheral faces facing said peripheral wall rotatably mounted onsaid eccentric, means for providing a fixed speed ratio between saidrotor and said crankshaft so that said crankshaft is caused to rotate assaid rotor planetates with a fixed cyclic relationship of threecrankshaft revolutions for every rotor revolution, said rotor faces andsaid housing walls cooperatively providing three chambers that arespaced about and move with said rotor while varying in volume as saidrotor and said crankshaft rotate and reaching a minimum volume when theassociated rotor face is exactly opposite one of the cusps which thendivides the chamber into a trailing portion and a leading portion andreaching a maximum volume intermediate the cusps, an intake port open tosaid cavity at a location on one side of one of said cusps so as to beconnected to deliver a gas to said chambers, a spark plug mounted insaid housing having an electrode open to said cavity at a locationadjacent the other cusp so as to be periodically exposed to saidchambers when they span said other cusp, a passage in said housinghaving an inlet open at one end to said cavity at a location on one sideof said other cusp and an outlet open at the other end to saId cavity ata location on the other side of said other cusp to provide forconnection between the trailing and leading portions of said chamberswhen they span said other cusp, a one-way valve in said passage forpermitting gas flow from the trailing portion to the leading portion ofsaid chambers when they span said other cusp and preventing gas flowfrom a leading chamber to a trailing chamber when a rotor apex isintermediate said inlet and said outlet, and an exhaust port open tosaid cavity at a location on the other side of said one cusp so as to beperiodically connected to exhaust said chambers.